Extruder vent flow sensor

Abstract

Disclosed are techniques for mitigating vent flow into a vent attachment on an extruder vent of an extruder. The vent attachment has a vent attachment port configured to release gases from the extruder vent. The techniques include monitoring temperature via a temperature probe mounted at least partly inside an interior opening of the vent attachment. The temperature probe is communicatively coupled to a programmable logic controller (PLC). A region of the vent attachment adjacent the temperature probe is cooled so as to reduce an operating temperature of the region and of the temperature probe. Vent flow is detected in response to the PLC determining a rate of temperature change of the temperature probe exceeding a predetermined threshold rate and thereby indicating presence of the material in the vent attachment port.

1 . A method of mitigating vent flow into a vent attachment on an extruder vent of an extruder, the vent attachment having a vent attachment port configured to release gases from the extruder vent, the method comprising:
 monitoring temperature via a temperature probe, the temperature probe having a free end and a fastened end, the free end located in the vent attachment port, and the fastened end being communicatively coupled to a programmable logic controller (PLC);   cooling a region of the vent attachment adjacent the temperature probe so as to reduce an operating temperature of the region and of the temperature probe, the operating temperature being below that of material flowing out of the extruder vent; and   detecting the vent flow in response to the PLC determining a rate of temperature change of the temperature probe exceeding a predetermined threshold rate and thereby indicating presence of the material in the vent attachment port.   
     
     
         2 . The method of  claim 1 , further comprising cooling the region by coupling a cooling jacket to an outer surface of the vent attachment. 
     
     
         3 . The method of  claim 2 , further comprising cooling the region by pumping coolant through the cooling jacket. 
     
     
         4 . The method of  claim 1 , further comprising cooling the region by pumping coolant through a cooling channel associated with the vent attachment. 
     
     
         5 . The method of  claim 1 , in which the vent attachment is an atmospheric vent stuffer. 
     
     
         6 . The method of  claim 1 , in which the vent attachment is a vacuum vent stuffer having a vacuum in the vent attachment port. 
     
     
         7 . The method of  claim 1 , in which the vent attachment is a vent tower having a vacuum in the vent attachment port. 
     
     
         8 . The method of  claim 7 , further comprising removing the vacuum from the vent attachment port in response to detecting the vent flow. 
     
     
         9 . The method of  claim 1 , in which the vent attachment is an atmospheric vent tower. 
     
     
         10 . The method of  claim 1 , further comprising cooling the material in the vent attachment port to at least partly solidify it preparatory to its removal from the vent attachment. 
     
     
         11 . The method of  claim 1 , further comprising generating an indication of the vent flow. 
     
     
         12 . The method of  claim 11 , further comprising presenting the indication on a human-machine interface (HMI) of the PLC. 
     
     
         13 . The method of  claim 1 , further comprising changing rotation speed of an extruder screw in response to detecting the vent flow. 
     
     
         14 . The method of  claim 1 , further comprising shutting off a material feed supply to the extruder in response to detecting the vent flow. 
     
     
         15 . The method of  claim 1 , further comprising receiving a value to configure the predetermined threshold rate. 
     
     
         16 . A programmable logic controller (PLC) for controlling an extruder, the extruder having an extruder vent to which a vent attachment is mounted, the vent attachment having a vent attachment port configured to release gases from the extruder vent, the PLC including a machine-readable storage medium storing instructions thereon that, when executed, configure the PLC to:
 monitor a temperature probe communicatively coupled to the PLC, the temperature probe having a free end located in the vent attachment port;   control a cooling system for cooling a region of the vent attachment adjacent the temperature probe so as to reduce an operating temperature of the region and of the temperature probe, the operating temperature being below that of material flowing out of the extruder vent;   determine a rate of temperature change of the temperature probe; and   generate an indication of vent flow in response to determining the rate of temperature change exceeds a predetermined threshold rate.   
     
     
         17 . The PLC of  claim 16 , in which the instructions further configure the PLC to receive the predetermined threshold rate. 
     
     
         18 . The PLC of  claim 16 , in which the instructions further configure the PLC to present the indication on a human-machine interface (HMI). 
     
     
         19 . The PLC of  claim 16 , in which the instructions further configure the PLC to remove a vacuum from the extruder vent in response to detecting the vent flow. 
     
     
         20 . The PLC of  claim 16 , in which the instructions further configure the PLC to change rotation speed of an extruder screw in response to detecting the vent flow. 
     
     
         21 . The PLC of  claim 16 , in which the instructions further configure the PLC to shut off a material feed supply to the extruder in response to detecting the vent flow. 
     
     
         22 . A system to mitigate vent flow into a vent attachment on an extruder vent of an extruder, the vent attachment having a vent attachment port configured to release gases from the extruder vent, the system comprising:
 a temperature probe having a free end and a fastened end, the free end located in the vent attachment port, the fastened end being communicatively coupled to a programmable logic controller (PLC);   a cooling jacket configured to cool a region of the vent attachment adjacent the temperature probe so as to reduce an operating temperature of the region and of the temperature probe, the operating temperature being below that of material when it flows out of the extruder vent; and   the PLC configured to determine a rate of temperature change of the temperature probe exceeding a predetermined threshold rate that indicates presence of the material in the vent port.   
     
     
         23 . The system of  claim 22 , in which the cooling jacket is a cooling plate mounted to a side of the vent attachment. 
     
     
         24 . The system of  claim 22 , further comprising a vacuum pump coupled to the vent attachment. 
     
     
         25 . The system of  claim 22 , in which the vent attachment is a vacuum vent stuffer.